Lemon myrtle (Backhousia citriodora) is a citrus-fragranced spice that is native to coastal regions of Australia. Its use as a flavoring agent in cooking is limited primarily to Australian cuisine, but it is slowly taking hold in regions around the globe where it has migrated, particularly in the southern portions of Europe and the United States, and South Africa.
The lemon myrtle tree is generally petite but can occasionally attain a height of over 60 feet (20 meters). The fragrant leaves, which are 2 to 5 inches (5 to 12 centimeters) long, are dark green, glossy, and lanceolate, or lance-shaped. The small, cream-colored flowers of the tree grow in clusters at branch tips throughout the summer season.
Lemon myrtle trees are also grown in regions of China and Southeast Asia, where the spice leaf is prized for its essential oil, which is used for both culinary and medicinal applications. The taste is bright and citrusy, with a pronounced lemon flavor. The leaves may be used either fresh or dried. Dried leaves of good quality have an intense flavor that may rival the flavor of fresh leaves.
Because the flavor of lemon myrtle resembles that of the citrus fruit so closely but lacks the fruit's acidity, it is especially useful in recipes that are milk- or cream-based. It imparts a strong lemony flavor and won't cause dairy products to curdle. On the other hand, it is unsuitable for extended cooking times, as the lemon flavor begins to dissipate and a strong eucalyptus flavor can begin to emerge. For this reason, this spice is more successfully used to flavor cookies, ice creams and sorbets, pasta, stir-fries, fish, and grilled meats than foods requiring longer cooking times, such as roasts and dense cakes.
In addition to its use in prepared dishes, lemon myrtle is a good choice to add flavor to spice rubs and marinades for poultry and fish, flavored vinegars, salad dressings, and dips. It can even be used as a flavoring agent in hot or iced tea.
The essential oil obtained from lemon myrtle contains antimicrobial compounds and is often used as an ingredient in shampoos, therapeutic body lotions, soaps, and household cleaners. The oil is believed to possess the ability to repel fleas and is therefore a feature of some chemical-free pet shampoos.